Educational device



Aug. 24, 1948. w. R. HQLT Re. 23,030

EDUCATIONAL miner:

Drigihai Filed June 29, 1944 Fig.

1. P-Sl 4-. '47 2. mu 5 615 D INVENTOR Wende R. Holt ATTOR Reissued Aug. 24, 1948 EDUCATIONAL DEVICE Wendell R. Holt, Aberdeen, Md.

dated June 18, 1946, Serial Original No. 2,402,162,

No. 542,791, June 29, 1944.

Application for reissue June 2, 1947, Serial No. 751,652

18 Claims. (01. 35-1) (Granted under the act of March 3, 1883, as

amended April 30, 1928; 3'70 0. G. 757) The present invention relates to educational devices, and more particularly to an automatic, self-operated machine to facilitate self-education and to give an indication of proficiency by self-operated scoring means.

The principal object of the invention resides in the provision of a device for automatically displaying an illustration or visual representation and a plurality of phrases relating to the illustration including correct and incorrect designations pertaining to the illustration or visual representation, together with a multiple choice selecting mechanism and scoring means for automatically indicating whether the correct designation is chosen.

A further object of the invention resides in the provision of a device as described above, together with means for displaying the correct designation associated with each illustration at a time after the multiple-choice designation has been selected by the student, in order that the student will be informed of the correct designation even though he may make an erroneous des ignation selection.

A further object of the invention resides in the provision of a unique multiple-choice scoring system comprising a scoring area or portion on a transparent film frame for registering a score together with a photoelectric means and shutters to indicate the correct or incorrect choice of multiple-choice designations.

Another object of the invention resides in the provision of a device as described above wherein the pictures displayed are projected onto a backlighted screen in order to provide an illustration and phrases relating to the illustration sufliciently large to be easily examined and clearly visible to at least several persons simultaneously.

Further objects will be apparent hereinafter.

Before describing the detail of the structure illustrated in the drawing and chosen as best illustrative of the principles of the invention, it is believed pertinent to point out that the inventor recognizes the existence of certain devices arranged to display an illustration together with multiple-choice answers, and to indicate the correct choice of an answer. So far as is known, however, all of such prior devices have been highly objectionable in certain features and it is submitted that the present invention, by overcoming the objections to the prior art structures, makes a substantial and valuable contribution to the art.

In considering the various characteristics of the present disclosure it should be kept in mind that machines of this character may be used in the training of military personnel in technical matters. When so used, it is important to provide as high a degree of amusement and maintain as high a degree of competitive spirit as possible. In this connection, it may be pointed out that in all naval training stations the educational schedule is very intensive, and that self -operated devices having no factor of amusement are of little Value. that machines of the character here disclosed provide a suiiicient degree of amusement so that even after personnel have spent a full day in formal class room or field study, they will find sufficient amusement in the operation of the machine to utilize their spare time in recreation rooms and barracks in manipulation of the device and in competitive eiiorts to obtain a good score.

Further, in a device designed for use in crowded quarters, as, for example, in enlisted mens barracks, it is desirable that the teaching capacity of the device shall not be limited to one person, but shall include several or many. One of the most serious deficiencies of prior devices of this character is that they ordinarily display a relatively small illustration, placed deep below a small window or lens, so that it is difiicult to observe and so that it may b seen only by one person at a time. Obviously, such an arrangement does not foster the development of a competitive spirit between members of a roup.

In contrast to this, the present device projects a sufiiciently large illustration on a screen so that it may be viewed by many persons at any reasonable angle, and within any reasonable distance from the screen; so that as one person operates the mechanism and makes his choice of the designations or phrases in relation to the i1- lustration, others may observe what is being done and observe the correctness or inaccuracy of the designations as they are given. With this arrangement, a greater incentive for competition is presented and, since the phrases pertaining to the illustrations are in sufiiciently large print so that they may be easily read, the continued operation of the device is not tiring to the student.

In general, the invention contemplates the provisionof an automatic machine having an external screen of relatively large dimensions so positioned that it may be viewed by a number of persons simultaneously. In addition to the screen, the cabinet of the machine will be provided with a plurality of designation selecting buttons and a scoring dial so that as each illustration is presented, the student may make a It has been discovered, however,

each frame includes an illustration, a plurality of multiple-choice designations, or whichone is I correct, and an identified correct designation corresponding to one of the multiple-choice-designations. In addition, each frame of the film includes a scoring portion or area which'will cause the machine to register the correct or in-- correct designation on the scoring mechanism when the selecting key'is depressed.

Therexact. form of the invention illustrated in the; drawing attached to and forming a part of the: present specification is included. by way of illustration rather than limitation, but it de scribes and illustrates, one possible manner in which the; principles. of the invention: may be utilized.. However, it is. recognized. that many minor modifications may be: made, and that various departures from the exact; structure or wiring' system illustrated in: the drawing. can be indulged. in withoutv departing from the inventive spirit.

Referring now: more ing: I

Figure 1 isacentral sectional view throughthe cabinet of a device illustrative of theprinciples of: the present invention;

Figure 2-1 is a. tragmentalr detail view' of a portion: ofthe continuous strip filmxutilized in the invention; and

Figure 3 is a: schematic block diagram ofi'one control circuit whereby the functions of the in-. vention may be accomplished.

The machine comprises, ingeneral, a cabinet I lI i-n which all of the working partsof: the mechanism are enclosed. The forward top portion ofthe-cabinet is provided with an inclined portion I l in which a translucent screen [2 is mounted. The screen [2 is rectangular in form and extends substantially the full widthbetwe-en the side walls of the cabinet. The height ofthescreen approximates the entire height of the inclined portion ll ofthe cabinet.

The cabinet is also provided with a plurality of multiple-choice designation selecting buttons P3. In the form illustrated, these buttons l8 are arranged in a transverse line across the shelf M or the cabinet. Any suitable number of selecting buttons may be used. The number ofbuttons should, however, correspond to the number of possible designations listed on the illustrations projected on the screen [2: In the device shown, six' designation selecting buttons are used and each button is numbered to corre spond with the designation list on each illustra tion. Each ofthe selecting buttonsis arranged to operate a. pair of' electric contacts IS-and l6 mounted on suitable insulated mounts H. The buttons are mechanically'interlocked to prevent simultaneous closing ofmore than one" pair of contacts. Enlarged pictures are projected-on the secreen [2* by the projector is; the lens I9: of which is directed toward amirror 21* on the, sub base 2-2 of the cabinet. 'Iheli'gh-t projected from particularly to the. draw- 4 the lens I9 is redirected upwardly to the mirror 23 and reflected from the mirror 23 directly onto the screen 12.

Examination of Figure 2 will disclose that, in the exemplary-embodiment shown, each frame of the film includes a center portion 24 having an illustration, and phrases relating to the illustration inculding a, question, and series a six possible designations or answers. This area 2:2 is positioned in the central portion of the film frame which is projected on the screen 82 at all times. Immediately above this portion 24 of the film is a correct answer designation area or portion which, when projected through the mirrors 2! and 2-3 will fall on the back surface of an opaque correct answer-concealing shutter 27. The shut ter 21 is magnetically operated by the solenoid 2'9; Thus when the film is projected onto the screen with the shutter 27 in the position illustrated, the upper portion of the screen will be blank, and the picture visible on the screen will include only the illustration, the question, and the multipleechoice designations. The identified correct. answer designationwill' be re vealed only: after one of the selector buttons l3 have been. depressed.

E achf'rame of the film also includes a scoring portion or area 32 having six separatescoring zones 35 to 40 inclusive, corresponding tothe multiple-choice designations or answers and. positioned'along one edge of the.frame, so that when a beam of light is projected through a transparent one of the scoring'zones itwill bedirected through the mirrors 2| and 23, will be. blocked by one of the banks of scoring shutters 33, unless the shutter has been lifted'by one of the solenoids 34.

The several multiple-choice. designations or answers shown on the film illustrated include one correct answer and five incorrect answers. Thus five o1- the-six scoring zones in the designation or answer area 3-2 will have completely opaque surfaces and one will" have a transparent portion so that a, beam of light will be transmitted through the film to the photoelectric cell. 42 unless blocked by one ofthe shutters 3-3. I is conceivable, of course, that a series of multiplechoice designations or answers may be provided to-which morethan one designation or answer is correct. For example, if the answers numbers I, 2, 4, and 6 were incorrect and the answers 3 and 5 were correct, the scoring zones 35, 3t, 38, and 46' would be entirely opaque and the zones 31 and 38 would include a transparent portion. Also, it is contemplated that one or more photocells 42 may beemployed.

When the frame of film is projected from the lens IS of the projector [8, light emitted from a transparent portion in any of the scoring zones will be reflected through the. mirrors 2i and 23 onto one of the shutters 33-. As long as the shutters 33am in the position illustrated in Figure 1, the light from the projector will have no effect on the-photoelectric cells 42' behind the shutters. However, if a button Iii corresponding to a correct designation or answer has been depressed, the shutter 33- operated by that button, and corresponding to the correct designation scoring zone having a transparent portion, will. be moved out ofthe path of the ray oflight and the light will fallon the photoelectric means 42'. This will operate through the amplifier 43- and timer M, to cause the device to indicate a correct-score on thescoring device 41.

' "The operation of the device is as follows: The

student desiring to use the machine will depress the start button 48. This starts the timing and sequence unit 44, which then controls the entire operation of the machine, and automatically displays a series of illustrations as, for example, a series of ten separate frames of the film shown in Figure 2. The first function of the timer 44 will be to close the power circuits which extend from the plug 45 to the projector l8, the photoelectric cell, amplifier 43, counter 41, question or frame number indicator 4B, and to each of the several designation or answer selector circuits 5| to 56 inclusive. The projector lamp will be energized and will project on the screen the central area 24 of a given frame of the film. .This will display the illustration, the question, and the series of multiple-choice answers or designations, but the identified correct answer or designation portion of the film 25 will be concealed by the shutter 21. Also a light beam will be projected through the transparent correct designation or answer scoring zone, but is stopped by one of the shutters 33. The student will observe the illustration, choose what he believes to be the correct answer from the multiple-choice answers, and depress the selector button l3 numbered to correspond with the answer or designation he has selected on the illustration.

If a, correct designation or answer is chosen, and the contacts I5 and i6 are closed, the winding of the solenoid 34 is energized and the corresponding shutter 33 moved out of position, the beam of light projected through the corresponding correct designation scoring zone will reach the photocell 42. The photocell is connected to the circuit of the counter through the amplifier 43 and the timing unit 44 so that when the photoelectric cell is energized the scoring unit 4'! will register a correct score.

When an incorrect designation or answer selector button 13 is depressed, the circuit through the solenoid winding 34 associated with that particular button and with the particular incorrect designation scoring zone on the film will be energized and its shutter will be moved out of the path of travel of the light channel. However, since the designation or answer is incorrect, no light will be transmitted through the opaque film zone, and light transmitted through the correct channel will be blocked by one of the other shutters. Thus no light will reach one of the photoelectric cells 42, and no score will be registered thereby.

When the allotted time for actuating the correct designation or answer button I3 has expired, the timer 44 will automatically register an incorrect response, energize the question counting unit 45 to indicate that the second question is about to be presented, and will energize the motor of the projector 18 to advance the film to the next frame. It is to be noted, however, that the timing and sequence unit 44 includes means to energize the solenoid coil 29, open the correct designation or answer concealing shutter 21 and display the correct designation or answer on the screen after a choice has been made by operation of one of the selector buttons I3.

When the entire series of frames of the film has been completed, the timer and sequence unit 44 breaks the circuits to the scoring unit 41, projector l8, amplifier 43, question number indicator 46,,and will also break an internal holding circuit across the pushbutton 48 so that further operation of machine can be accomplished only by beginning a new cycle. This is done by 6 depressing the starting button. The completion of the cycle will leave the final total score registered on the counting mechanism so that it may be observed after the cycle has ended.

When the timing or starting button 48 is again depressed to start a new cycle, the timer will momentarily energize the counter to reset it to zero simultaneously with the projection of the first picture on the screen.

Since it has heretofore been pointed out that the particular structure and arrangement of parts illustrated in connection with this invention are intended for purposes of illustration and are subject to many modifications and variations, the scope of the inventive thought should be considered as limited only by the prior art and the terms of the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. In apparatus including a closed cabinet and a translucent screen comprising a portion. of said cabinet with an optical projector within the said cabinet to project light through a film to project the film image on to the inner surface of said screen, a film comprising a multiplicity of individual frames inter-connected to form a continuous endless loop, each of said frames bearing a visual representation, a plurality of designations including correct and incorrect designa-- tions relating to said visual representation, and a scoring portion having scoring zones thereon corresponding to the aforementioned designations, the correct and incorrect scoring zones being of unlike light transparency, and scoring means including means actuated by light transmitted through a correct designation scoring zone for registering a score.

2. In apparatus including a closed cabinet and a translucent screen comprising a portion of said cabinet and an. optical projector within said cabinet to project light through a film to project the film image on to the inner surface of said screen, a film bearing a visual representation, a plurality of designations including correct and incorrect designations and an identified correct designation relating to said visual representation, and a scoring portion having scoring zones corresponding to said correct and incorrect designations, and scoring means including a plurality of separate individually operable shutters and manually operable controls corresponding to and adapted to actuate said shutters to permit the passage of any light passing through the scoring portion of the film to register a score, a designation concealing shutter to conceal the identified correct designation. projected from the film and means responsive to the operation of any one of the aforementioned manually operable controls to open the designation concealing shutter.

3. In apparatus includin an optical projector and screen, a film bearing an illustration, a plurality of designations and an identified correct designation relating to said illustration, and a scoring portion, scoring means including a plurality of separate individually operable shutters and manually operable controls corresponding. to and adapted to actuate said shutters to permitthe passage of any light passing through the scoring portion of the film to register a score, ades'ignation concealing shutter to conceal the identified correct designation projected: from. the film, and means. responsive to the operation of any one of the aforementioned manually operable controls toopen the designation concealing shutter.

4. In apparatus including an optical projector and screen, a film comprising: a continuous-endless strip made up of a multiplicity of: individual frames, each frame of which'bears an illustration, aplurality of designations and an identifiedcorrect designation relating tosaid' illustration, and av scoring portionincludingat least one transparent zone and at least one opaque zone, and scoring means including: means. actuated byxlight transmitted through a transparent zone for registering a score.

5. In apparatus including an optical projector and screen, a film including an illustration; a plurality ofdesignations includlnga correct designation relating-to said illustration, anda scoring portion including at least one transparent zone and at least one opaque zone, separateindividually operable shutters corresponding to each of said zones including a shutter controlling the light projected'through the transparent zone, and separate manually operable controlscorresponding toand adapted toactuate each of. said shutters, at least one photoelectric cell to receive a ray of light projected throughthe.trans-, parent zone of the scoring portion, and. means responsive to the action of the photoelectric cell to indicate that the manual-control corresponding to the correct, designation; has been actuatedby registering a correct score.

6. In apparatus including anoptical projector; and screen, a film comprising. a continuous endless strip made up of a multiplicity of; individual frames, each frame of which'bears-a; visual-rep,- resentation, a plurality of designations and an identified correct designation relating to said visual representation, and a scoring; portion including atleast one transparentzone and at; least one opaque zone, separate individually operable shutters one-for each of said zones in the scoring portion, at least one of said shutters normally lying in the path of a ray of light projected through a transparent zone,, and menu? ally operable controls corresponding to adapted to actuate each of said shutters tomove them out of the path of any light passing ;throug;h the corresponding zone, a designation, conceah ing shutter to conceal the identifiedcorrect-designation projected. from the film, rne a nsresponsive to the operation of any one opf' the aforementioned manually operable controls to open; the correct designation coneealingshuttenatleast. one photoelectric cell in the path, oilight pros. jected from a transparent zone of said scoring portion, and scoring means responsive to theao: tion of. the photoelectric cell, to indicate thatgthe manual control corresponding to-the correctdesignation has been actuated, byregistering; a score.

7. Educational apparatus comprising'an optical projector adapted for cooperation withan element bearing an image: including; a score determining portion, a screeniarrangedto receive a projected imagev from said element and pro-- jector, scoring means responsive totheeiiiectoi said scoring portion upon light. from said projector and manualselection meansufor. actuating; said scoring means.

8. Educational, apparatus comprising. on 011131:- calprojector adapted forv cooperationwith acombined. subject, answerand scoring image. bearscoring means responsive: to the eflect of: said scoring: image upon lightv from said projector, a

plurality of manual-selection means for presentingsaid. answer image on said screen, and certain of said: selectionmeans also actuating said scoring mean-slf'ora: particular scoring image.

9. Educational apparatus comprising an optical.=projector-adapted: for. cooperationwith a combined subject and scoring image bearing element, a screen arranged to: receive a projected. image from saidelement and projector, manual selection means for actuating: said element, andph-otoelectric means actuated" by certain of: said: selectionmeans in response to. the properties. of said scoring; image for: transmitting. light from said projector.

10. Aouiz machinecomprising a; projector,- a screen, a photographic film having thereon a question, a plurality'of possible" answers and; the

correct answer, which is, one of said: possible an,- swers. means-,for operatingthe projectorrtopro- 18. .1 said question. plurality of: possible answers and correct; answertoward: the; screen,v a; shutter forxobscuring the correct: answer; from view, the questionv and plurality of: possible answers bein unobstructed and adaptedto be: initially thrown onto, thescreen, a plurality'ofe selectors, one for each ofisaid possible answersmeansactuated by n ration, of any, Qneof saidt electiors. fQITemoving. said: shutter from: obscuring position, to. bring the, orrect. answer into view' on the screen.v a correct answer indicating: device, findmeans actuated by: operation of; the, selector. for the; correct answer.- toioperate said-indicating device.

1- A- qu z machine compr g a nr i,s o .,in.- eluding a scur eof l ght ascreema phot ra film having thereon a question; a: plurality of possible, answers, and; the, correct answer; which s. one. of? aid: poss ble ans rs sa d fi m; hav a clear; sectio therein, positioned. in, prcdet n mined relation to the One; of said; possible answers whichisthe correct one n' eansfor operat nsthe proiect r o p ect. sai question. plurality fip ssible answerszandcorrect, answer toward the soreen, a,shutter for obscuringthe correct answer from. view, t e ue ti n, and Pl s rality. of possi le nsw rs. ein un b tructedand adapted: to b initiallx thrown onto;v the screen. a/plur lity o ele ors, on or. ach of;said.pos.- si le a sw rs. m ans actuated by. op at on. of any one of said selectors for removing saidshutter, from obscurin position to bring the -correct nswerinto V ew on thesczre n, a correctanswer n catingler cal nd: m ns actu ted by operat on of. the selectorfor; the correct nswer perate, said. indicating evice said last. men; qn cl: means including; ali h sen it ve: device a p ed o baenersized by'l s fr m the-source ioresaid pas in h o h said c ar section: in t lm. ahu r normally p e entin u h ish fr m. r a hin said, lish r n i ive evice. and m ans perated. by, s idcorrect nswer 56* lector for rem n a d- ESL-mentioned. shutter r m l h -ob tr tin position;-

A q iz'm chine comprising-a proiectonim iludina aisource of light, a screen. a photographic having t er on; a question; a; plurality of possible; answers. and thecorrect answer, which is one. ofzsaid possible, answers, said film. having a, clear section; therein positioned: in, predeters mine darelation to the oneof said: possible answers whichiisthezcqrrect one; meansion operating the projector: to; project said; question, plurality of 9. possible answers and correct answer toward the screen, a shutter for obscuring the correct answer from view, the question and plurality of possible answers being unobstructed and adapted to be initially thrown onto the screen, a plurality of selectors, one for each of said possible answers, means actuated by operation of any one' of said selectors for removing said shutter from obscuring position to bring the correct answer into view on the screen, a correct answer indicating device, and means actuated by operation of the selector for the correct answer to operate said indicatin device, said last mentioned means including a light-sensitive device adapted to be energized by light from the source aforesaid passing through said clear section in the film, a plurality of light channels, a reflector for directing said light into one of said channels determined by the position of said clear sections in the film, a normally closed shutter in each of said channels and means operated by'the particular selector operated for withdrawing a corresponding one of said lastmentioned shutters, withdrawal of the shutter corresponding to the correct answer selector permitting said light to pass through the channel which is normally closed by said shutter onto said light-sensitive device 'to energize the same and thereby cause operation of said indicating device.

13. A quiz machine comprising a projector, including a source of light, a screen, a photographic film having thereon a question, a plurality of possible answers and the correct answer, which is one of said possible answers, said film having a clear section therein positioned in predetermined relation to the one of said possible answers which is the correct one, means for operating the projector to project said question, plurality of possible answers and correct answer toward the screen, a shutter for obscuring the correct answer from view, the question and plurality of possible answers being unobstructed and adapted to be initially thrown onto the screen, a plurality of selectors, one for each of said possible answers, means actuated by operation of any one of said selectors for removing said shutter from obscuring position to bring the correct answer into view on the screen, a correct answer indicating device, and means actuated by operation of the selector for the correct answer to operate said indicating device, said last-mentioned means including a photoelectric cell adapted to be energized by light from the source aforesaid passing through said clear section in the film, a sensitivity amplifier and a relay in series with said photoelectric cell, a switch on said relay for closing a circuit to said indicating device, a shutter for normally preventing said light from reaching said photoelectric cell, and electrical means operated by said correct answer selector for removing said last-mentioned shutter from light-obstructing position.

14. A quiz machine comprising a projector, a screen, a length of photographic film having thereon a plurality of frames each including a question, a plurality of possible answers and the correct answer, which is one of said possible answers, means for operating the projector to project the contents of one of said frames toward the screen, a shutter for obscuring the correct answer from view, the question and plurality of possible answers being unobstructed and adapted to be initially thrown onto the screen, a plurality of selectors, one for each of said possible answers, means actuated by operation of any one of said selectors for removing said shutter from obscuring position to bring the correct answer into view on the screen, a correct answer indicating device, means actuated by operation of the selector for the correct answer to operate said indicating device, and

means for advancing said length of film upon each operation'of the machine to cause a new frame to be brought into proj ecting position.

15. A quiz machine comprising a projector, a screen, a length of photographic film having thereon a plurality offrames each including a question, a plurality of possible answers, the correct answer, which is one of said possible answers, and a clear section positioned in predetermined relation to the one of said possible answers which is the correct one, means for operating the projector to project the contents of one of said frames toward the screen, a shutter for obscuring the correct answer from view, the question and plurality of possible answers being unobstructed and adapted to be initially thrown onto the screen, a plurality of selectors, one for each of said possible answers, means actuated by operation of one of said selectors for removing said shutter from obscuring position to bring the correct answer into view on the screen, a correct answer indicating device, means for moving said film upon each operation of the machine to present a new frame for projection, and an integrator for causing operation of said indicating device when the right answer is selected, said integrator comprising a photoelectric cell, means whereby said indicating device is operated by energization of said photoelectric cell, and means whereby light passing through the clear section in said film is caused to reach said photoelectric cell to energize the same by operation of the correct answer selector but is prevented from reaching said cell when any other of said selectors is operated.

16. A quiz machine comprising a projector, a screen, a length of photographic film having thereon a plurality of frames each including a question, a plurality of possible answers, the correct answer, which is one of said possible answers, and a clear section positioned in predetermined relation to the one of said possible answers which is the correct one, means for operating the pro- J'ector to project the contents of one of said frames toward the screen, a shutter for obscuring the correct answer from view; the question and plurality of possible answers being unobstructed and adapted to be initially thrown onto the screen, a plurality of selectors, one for each of said possible answers, means actuated by operation of one of said selectors for removing said shutter from obscuring position to bring the correct answer into view on the screen, a correct answer indicating device, means for moving said film upon each operation of the machine to present a new frame for projection, and an integrator for causing operation of said indicating device when the right answer is selected, said integrator comprising a photoelectric cell, means whereby said indicating device is operated by energization of said photoelectric cell, and means whereby light passing through the clear section in said film is caused to reach said photoelectric cell to energize the same by operation of the correct answer selector but is prevented from reaching said cell when any other of said selectors is operated, said last-mentioned means comprising a plurality of shutters, one corresponding to each of said selectors, and individual electrical operating devices for said shutters arranged to be energized by said selectors, respectively, whereby operation of one'of theselector's causes withdrawal of the corresponding shutter permitting such light to pass *to-said photoelectric cell if the :selectoroperated is the one '-'for i the right answer.

1'7. A quiz machine comprising a projector, a screen, a length of photographic film having thereon a plurality 'of frames each including a question, a plurality of possible answers, the correct answer, which is one of said v-po'ssible answers, and a clearscction positioned in predetermined relation to the one 'of said possible answers which is the correct one, means foroperating the projector to project the contents of one of said-frames:towardthe'screen, a shutter for obscuring the correct'answer from View, the question and plurality of possible answers being unobstructed and adapted to be initially thrown onto the screen, a plurality of selectors, :one :for each of said possible answers, means actuated by operation of one of said selectors for removin-g said shutter from obscuring position tobring the correct answer into view on the screen, -a correct answer indicating device, means'f0r moving said only when the right *answeris :selected.

18. A quiz machine comprising a proj ector, a screen, "a photographic film having thereon a question, a. :plurality "of possible answers and the correct -answer, which is one 101' said possible answersfmeans fonoperating the vprojector to pro- J'cct said -question, plurality of *possible answers and correct answer toward the screen, -a shutter for :obscm'ing the a correct :answer from view, the question :and plurality of possi ble answers being unobstructed :and adapted to be initiallyrthrown onto :the screen, a :purality-ofselectors, one for each .of 'said :possible answers, means for removing :saidshutter "from-obscuring position to bring the correct answer into view on the screen, a correct-answer indicating device, and means at:- tuated-by-operationof the selector for the correct -'-'answer :to operate said indicating device. WENDELL R. HOLT. 

